Evaluation of Threshold and Prethreshold Lights for Medium Intensity Approach Lighting Systems

This report describes the evaluation of runway threshold lights for use with medium intensity approach lights with runway alignment indicator (strobe) lights (MALSR) systems. Three different lamps and fixtures were selected for final evaluation. Based on flight tests and photometric measurements, it was concluded that 300-watt, 300PAR56/NSP lamps would provide the improved visual guidance and conspicuity of the threshold necessary for operations in visibility conditions as low as Category I, 2,400 feet runway visual range (RVR). The green threshold lights spaced 10 feet apart with the outer lights inline with the runway edge lights will conform to ALSF-l and ICAO criteria for Category I operations.

A supplementary test was conducted to evaluate proposed configurations of red wing bar lights in the prethreshold area to augment the threshold lights for improved visual guidance. The test results concluded that, with the bold and distinctive
threshold, red prethreshold wing bar lights did not provide appreciable improvement in guidance under the test conditions.